Effect of heating on the physical properties of asphalt aggregates

Abstract

Asphalt is defined as a mixture of inert mineral matter, such as aggregate, mineral filler and bituminous binder in predeterminated portions. One of the most important properties of asphalt mixtures is the bitumen content. The most preferred way of asphalt binder analysis is extraction (with tricloroethylene). Because of environmental reasons extraction should be replaced with more environment friendly solution, this could be heating. But high temperatures can cause changes in the physical properties of mineral aggregates that are commonly used in asphalt mixtures causing faults in the results of the binder analysis. Eight different types (five andesites, one basalt, two dolomites) of Hungarian rocks have been tested in laboratory conditions to analyse the effect of heat on asphalt aggregates. 11/16 mm fractions were heated at 480^o C in an ignition furnace. The weight losses and grain distributions were recorded and compared. The physical parameters have shown that aggregates behave differently after burning on high temperature. As an additional result coloures and colour differences of aggregates were also observed after heating.